Restraint systems are now in widespread use in motor vehicles today. While seat belt systems provide a high degree of occupant impact protection, deployable impact protection devices such as inflatable airbags are now in commonplace use in motor vehicles. These systems incorporate a crash sensor which detects the onset of a vehicle collision and sends a crash signal to the inflatable restraint module. A source of gas is activated in response to the crash signal to inflate a fabric air cushion which is presented to absorb impact energy of the occupant within the vehicle. Such inflatable restraint systems are found mounted to steering wheels for driver side protection or mounted to instrument panel structure to provide protection for front seat passengers. These systems have been found to provide excellent occupant crash protection, particularly when used with a belt-type restraint system. Aiding in providing occupant protection for frontal impacts is the significant amount of deformable structure in the forward portion of the typical automobile. Moreover, today's crash sensors for sensing frontal impact provide reliable crash signals in a time period permitting deployment of the inflatable restraint system.
These advantages are not available when designing inflatable restraint systems for side impact collisions. Motor vehicle manufacturers and their suppliers of safety systems are increasingly focusing on deployable devices for providing side impact protection. Statistically, side impacts pose a greater probability of causing significant occupant injury as compared with frontal impacts. This difference is largely due to the limited energy absorption structure available in side impact situations, especially for "on side" occupants. In response to this concern, vehicle manufacturers and suppliers are developing side impact airbags which are mounted either to the door or body pillar structure, or to the seat back of the occupant seat. Similar to frontal impact systems, side impact systems incorporate a crash sensor which detects a side impact collision and generates a crash signal. In response to the crash signal, an inflator generates gas to inflate a woven fabric airbag which fills an area between the door and the occupant. The door structure acts as a "reaction plate" to support the airbag as it is compressed by the occupant thus providing energy absorption.
Numerous designs of inflatable restraint systems are available today. Current side impact modules are designed with similarities to passenger and driver frontal impact airbag modules. These modules are made up of many components including: a cushion, a cushion attachment, a retainer, and a cover. Also, current modules typically have many fasteners to attach the module components and to attach the module to the vehicle structure. Despite the effort exerted in optimizing the design of these devices, there is a continuing need to improve the manufacturability and cost of the systems while maintaining their reliability. Of significant importance is the reduction in the number of separate components which must be assembled to build the inflatable restraint system. The existence of a multiplicity of parts has a negative cost effect, both in terms of part fabrication and assembly.
In motor vehicle design today, size and mass constraints are of critical importance. This is especially true for the side frame area of an automobile body where there is a very tight packing space. To make effective use of packing volume in the automobile, it is desirable to reduce the overall size of an airbag module. In order to be cost effective, the design of a deployable side impact restraint device should be applicable across many vehicle platforms and provide low cost fabrication and assembly. Moreover, efforts to achieve benefits in these areas must not sacrifice the performance of the restraint system.
Thus, there is need for an improved side impact airbag module which can be produced at a lower cost. There is also a need for a side impact airbag module of reduced size and complexity. There is a further need for a side impact airbag module configured for simplified installation to the seat frame. There is a still further need for a side impact airbag module which provides performance flexibility across various vehicle applications.